ALGAE BLOOM AND BUST · 2 Set up the four jars so that all have equal amounts of bottled water and algae, and are exposed to the same light intensity. Label the four jars, and prepare

C E N T E R F O R E C O L I T E R A C Y

OVERVIEW

Climate change and increasing water

temperatures, along with added

nutrients from human activities,

impact both aquatic ecosystems and

the people who depend on them.

In this experiment-based lesson,

students examine one outcome:

algae blooms.

G R A D E L E V E L : 6–9

ALGAE BLOOM AND BUST

2

ALGAE BLOOM AND BUST CENTER FOR ECOLITERACY WWW.ECOLITERACY.ORG

Copyright © 2013 Center for Ecoliteracy

Published by Learning in the Real World

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No part of this report may be reproduced in any form or by any electronic or

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Berkeley, CA 94704-1377

For more information about this activity, email [email protected] or visit

www.ecoliteracy.org.

Learning in the Real World is a publishing imprint of the Center for Ecoliteracy,

a not-for-profit, tax-exempt organization. Created in 1997, Learning in the Real

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C E N T E R F O R

SMART BY NATURE™ downloadable resource

®

3


ALGAE BLOOM AND BUST

P U R P O S E

To learn about the possible effects of global climate change and human activities

such as farming and waste processing, students conduct an experiment on algae

and see how increases in nutrients and temperature can impact aquatic ecosystems.

G R A D E L E V E L

6–9

B A C KG R O U N D

Algae are simple, green aquatic plants that have no roots, leaves, or flowers.

Algae and other phytoplankton are important because they form the basis for

many aquatic food webs. They also produce most of the oxygen present in Earth’s

atmosphere. However, too many algae growing too quickly can wreak havoc on

an ecosystem.

Algae make their food through photosynthesis, a process that involves capturing

light energy from the sun and converting it to carbohydrates; photosynthesis

requires carbon dioxide and water, and releases oxygen. When algae metabolize

the carbohydrates through respiration, they get chemical energy to fuel growth,

reproduction, and other life processes.

4


Like other green plants, algae create and metabolize food through the

processes of photosynthesis and respiration.

P H O T O S Y N T H E S I S

carbon dioxide + water + light energy ➔ food (carbohydrates) + oxygen

R E S P I R AT I O N

food (carbohydrates) + oxygen ➔ chemial energy + water + carbon dioxide

The term algae bloom refers to a rapid rise of the algae population in a body of

water. Algae blooms are usually caused by moderate increases in water temperature

and excess nutrients—primarily phosphorus and nitrogen from crop fertilizers,

animal wastes, or sewage facilities. As such, they are unintended consequences of

some of the methods we use for growing food or processing waste.

The rapid increase of algae can have a drastic effect on an aquatic ecosystem. The

algae cover the surface of the water, blocking sunlight from beneficial underwater

plants that provide food and shelter for fish and other animals. When the algae

proliferate, they start to deplete the nutrient supply and die off. This, in turn, causes

a reduction of dissolved oxygen as the dead algae decompose, a process that uses

oxygen. Many fish and other aquatic organisms die when the oxygen level lowers.

The Earth’s climate is changing more rapidly than society has ever experienced in

the past. We have strong evidence that a dramatic warming trend is largely the

result of increased carbon dioxide and other greenhouse gases in the atmosphere

from the burning of fossil fuels, yet another example of an unintended consequence

of human activity. As global temperatures rise with climate change, more water

environments are becoming susceptible to algae blooms. Warmer weather has

(CO2) (H

20) (C

6H

12O

6) (O

2)

(C6H

12O

6) (O

2) (H

20) (CO

2)

5


created longer growing seasons, and has enabled more algae to grow in northern

waters previously too cold for their survival.

In addition to suffocating aquatic habitats, some species of marine algae produce

dangerous toxins that can be deadly to both aquatic and land life, including humans.

Called “harmful algal blooms” (formerly known as “red tides”), these dangerous

phenomena are occurring earlier and more frequently with climate change. Rising

temperatures and increasing levels of CO2 in the atmosphere—combined with

increased nutrients—are impacting the growth and relative abundance of harmful

algal bloom species.

M AT E R I A L S

• Algae sample (see Preparation)

• Four one-gallon glass jars or aquaria with covers

• Bottled or distilled water

• Four eyedroppers

• One bottle of liquid plant food

• Two identical aquarium heaters or other sources of heat (see Preparation)

• Thermometer

• Tape or grease pen for labeling jars

• Magnifying lenses

• Microscope (with at least 10x power) and slides

• Dissolved oxygen test kit (optional)

• “Algae Observation” student page

• “Story of an Algae Bloom” student page

6


P R E PA R AT I O N

• Four to eight days before doing the lesson, prepare the algae culture:

- Obtain algae from a freshwater pond or lake, or from a scientific supply

house (see Resources). You will need one dropperful of algae for each of the

four jars.

- Fill four jars with equal amounts of bottled or distilled water. (Tap water may

contain chlorine or other substances that would affect the experiment.)

- Place a dropperful of algae in each of the four jars. Let the algae culture

incubate four to eight days. This time period will let the algae adjust to the jar

environment and ensure approximately equal growth in each jar.

• Obtain two submersible aquarium heaters, set to the same temperature. For this

experiment, the ideal water temperature is 25–28˚C (75–82˚F).

(As an alternative, you can place the water containers on heating pads wrapped

in plastic bags and set on “low.” Test the temperature with a jar of water placed

on the heating pad. If the water gets above 28˚C [82˚F], enclose a book in a

plastic bag to create a spacer between the jar and the heating pad. Experiment

with one or more spacers until the water temperature remains constant at the

desired level for 12 to 24 hours.)

• Make copies of the student pages.

L E S S O N I N T R O D U C T I O N

Ask students to jot down a list of factors that plants need to survive and thrive

(such as water, sunlight, nutrients, carbon dioxide, ability to reproduce, etc.). After

students have had a few minutes to write, ask them to share factors from their lists.

Remind students of the relationship between global climate change and an

overabundance of carbon dioxide and other greenhouse gases in the atmosphere.

Ask, “What effect might rising temperatures have on plants? What effect would it

have on other organisms?” Ask them to think about what might happen if there was

an overabundance of any of the other factors.

7


C O N D U C T I N G T H E L E S S O N

1 Explain to students that they will conduct an experiment with algae to examine

the effect of an increase in two factors: temperature and nutrients. Ask, “What

are algae? Why might they be important for aquatic ecosystems?”

2 Set up the four jars so that all have equal amounts of bottled water and algae,

and are exposed to the same light intensity. Label the four jars, and prepare

them as follows:

- Jar A: water and algae only.

- Jar B: water, algae, and liquid plant food (add the amount recommended on

the label).

- Jar C: water and algae, with a heat source.

- Jar D: water, algae, and plant food (the same amount as Jar B), with a

heat source.

3 Distribute the “Algae Observations” student page. Ask students to predict

algae growth by rank ordering the jars, with a “1” for the jar they think will have

the most algae growth in 1–2 weeks, and a “4” for the jar they think will have

the least.

4 Every day or two for the next 1–2 weeks, direct students to observe the jars

and rank order the amount of algae they see, recording their results on the

“Algae Observations” student page. Take a drop from each culture, place it on a

microscope slide, and have students count and record the number of algae per

drop that they see. (Optional) Use the test kit to determine the level of dissolved

oxygen in each jar.

5 After observing the jars for 1–2 weeks, have students answer the questions on

the “Algae Observations” student page.

6 Divide the class into pairs for reading “The Story of Algae Bloom” student page,

and answering the questions that follow the story.

8


NOTE: Be sure to properly dispose of algae cultures. Do not pour them down the

drain without treating them first in one of the following ways:

1 Adding bleach to the culture in the ratio of 2 1/2 tablespoons to one gallon of

culture, and leaving it to sit overnight before pouring it down the drain with

running water.

2 Bringing the culture to a boil in a microwave-safe container in a microwave oven.

While this will cause an unpleasant smell, it will not contaminate your microwave

for future food use.

D I S C U S S I O N A N D W R A P - U P

Lead a discussion about students’ findings:

• Which treatment exhibited the most algae growth?

• What factors cause an algae bloom?

• Can you think of another situation in which “too much of a good thing” has a

negative effect on people or the environment?

• How might an algae bloom such as the one described in “The Story of an Algae

Bloom” be prevented?

• What might be the effect of global climate change and the resulting worldwide

increases in water temperature?

R E S O U R C E S

For live algae cultures and dissolved oxygen test kits:

• eNasco. www.enasco.com.

• Carolina Biological Supply. www.carolina.com.

• Ward’s Natural Science. www.wardsci.com.

9


S O U R C E S

This activity was adapted from:

Carolie Sly, Leslie Comnes, and Sandra Brislain. “Algae Bloom and Bust.” In Water

Wisdom: Curriculum for Grades Four through Eight. Alameda, CA: Alameda County

Office of Education, 1990).

The Background section includes information about the effects of climate change on

algae from:

“Climate Change and Harmful Algal Blooms.” National Oceanic and Atmospheric

Administration. Retrieved from http://www.cop.noaa.gov/stressors/extremeevents/

hab/current/CC_habs.aspx

“Harmful Algae Take Advantage of Global Warming: More Algal Blooms Expected.”

April 7, 2008. Science Daily. Retrieved from http://www.sciencedaily.com/

releases/2008/04/080403140928.htm

10


ALGAE OBSERVATION

Predict the growth of algae in 1–2 weeks by placing a “1” next to the jar you think

will have the most algae, and a “4” next to the one you think will have the least.

Jar A ____________ Jar B ____________ Jar C ____________ Jar D ____________

Each day of observation, rank the amount of algae in each jar (as in your prediction

above) and record other observations.

DATE DATE DATE DATE DATE

JAR A

JAR B

JAR C

JAR D

RA

NK

ING

BS

ER

VA

TIO

NS

RA

NK

ING

OB

SE

RV

AT

ION

S

RA

NK

ING

OB

SE

RV

AT

ION

S

RA

NK

ING

OB

SE

RV

AT

ION

S

RA

NK

ING

OB

SE

RV

AT

ION

S

Name_________________________________

11


Q U E S T I O N S :

1 At the end of the observation period, which jar had the most algae? ____________

2 Was your original prediction correct? If not, what might have caused this result?

__________________________________________________________________________

3 Did the rankings for each jar stay the same over time? ___________________________

4 How did plant food affect the growth of algae? Compare the amount of algae in

jars B and D to the control (jar A).

__________________________________________________________________________

__________________________________________________________________________

5 How did temperature affect algae growth? Compare jars C and D to the control (jar A).

__________________________________________________________________________

__________________________________________________________________________

6 Which had more effect: plant food or temperature? Compare jar B to jar C.

__________________________________________________________________________

__________________________________________________________________________

Name_________________________________

12


T H E S T O R Y O F A N A L G A E B L O O MA small lake sits in a farming area. When it rains, water runs off the surrounding

farmland, carrying traces of fertilizer and manure into the lake. Due to climate

change, the lake water is about 5 degrees (˚F) warmer than it was 50 years ago.

One summer, the warm water and nutrients cause an algae “bloom,” the rapid growth

of algae. The lake’s water appears green as the algae nearly cover its entire surface.

When the algae die, they sink to the lake bottom, where they are decomposed by

bacteria. This process of decomposition requires oxygen, and causes the level of

oxygen in the water to drop.

1 Draw a picture of the place described in the story.

Name_________________________________

13


2 What are possible consequences of a sudden increase in algae on fish and other

organisms living in the lake? How might these organisms be affected when the

algae die?

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

3 What are possible consequences of a lack of oxygen on other plants and animals

living in and around the lake?

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

4 Write a statement describing how people’s activities appear to impact the lake

and the organisms living in it.

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

5 If you lived near the lake and an algae bloom began, what might you do? To whom

would you go for help? How might this problem be prevented in the future?

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

Name_________________________________

14


A B O U T T H E C E N T E R F O R E C O L I T E R A C Y

The Center for Ecoliteracy is an internationally recognized leader in systems change

innovations in education for sustainable living. Since 1995, the Center has engaged

with thousands of educators from across the United States and six continents. The

Center offers publications, seminars, academic program audits, coaching for teaching

and learning, in-depth curriculum development, keynote presentations, and technical

assistance. Books authored or coauthored by the Center for Ecoliteracy include

Ecoliterate: How Educators Are Cultivating Emotional, Social, and Ecological Intelligence

(Jossey-Bass, 2012); Smart by Nature: Schooling for Sustainability (Watershed Media,

2009); and Ecological Literacy: Educating Our Children for a Sustainable World (Sierra

Club Books, 2005).

CREDITS

Authors Carolie Sly, Leslie Comnes

Editor Michael K. Stone

Designer Karen Brown

Production Monica Bueb

PHOTOS

Cover Algae: istockphoto 000018937146, NNehring

C E N T E R F O R

Documents

ALGAE BLOOM AND BUST · 2 Set up the four jars so that all have equal amounts of bottled water and algae, and are exposed to the same light intensity. Label the four jars, and prepare